Stenosis due to plaque in coronary vessels pose a threat to the health of a person as it hampers blood flow in the cardiovascular system of the person. Fractional flow reserve, a ratio of a first fluid pressure at a first point in a coronary artery divided by a second pressure at a second point in the coronary artery, upstream of the first point is accepted as a measure of the impact of stenosis on blood circulation in a vessel.
Blood pressures may be determined by means of intervention in the blood vessel under scrutiny with a pressure sensor. Such intervention involves a significant amount of work and poses a risk to the person under scrutiny as the vessel wall may be damaged by the pressure sensor. Methods of determining geometry of a cardiovascular system are available, like three dimensional or two dimensional quantitative coronary angiography—QCA. The output of such methods is used for elaborate numerical analysis of the vessel under scrutiny, for example by solving the complex fluid equations using computational fluid dynamics as proposed in a paper “Virtual Fractional Flow Reserve From Coronary Angiography: Modelling the Significance of Coronary Lesions, published in JACC: Cardiovascular Interventions. Such approach requires a significant amount of processing power.
Other approaches propose to treat a narrowing in a coronary artery as having a specific length and a fixed width, as presented in the paper Calculation the Translesional Pressure Gradients on Coronary Stenosis by Combining Three-dimensional Coronary Angiography Parameters with Frame Count Data, published in Computing in Cardiology. In particular the assumption of a fixed area of the narrowing reduces accuracy of the outcome of the calculations. In addition, it is subjective and not reliable to determine the length of the narrowing in practice, especially in patients with diffused and multiple coronary lesions.